Troubleshooting a refrigeration system is all about gathering information and using that information to determine the cause of a problem. Technicians are always measuring voltages, amperages, pressures, and various temperatures to help them find a problem. Besides these important measurements, there are other pieces of information that can assist a technician. A technician should spend some time with the customer and try to obtain some system history. Knowing what work was done on the system previously, or how the system had been operating up to the breakdown, can help in determining the current malfunction.
A good time for a technician to ask these questions is when first arriving on the job. Some questions to ask include:
• When was the system last repaired and what service was performed?
• Was the unit making any strange sounds before it broke down?
• Was it cooling effectively just before it failed?
Example 1:Suppose a technician discovers that last week another technician added refrigerant to the system and did not repair any leaks. It is a very good possibility the current problem is a low refrigerant charge and now the technician will need to locate and repair the leak before adding more refrigerant.
Example 2:Suppose a technician arrives to repair a reach-in cooler and after speaking with the customer discovers there was a strange sound coming from inside the cabinet last week, but the system seemed to be working OK. Now the sound is gone and the system is not working. This might lead a technician to first look at the evaporator fan motor as being the cause of the problem. Perhaps the evaporator fan motor was failing, thus producing the strange sounds and now the motor has totally failed.
Example 3:Asking some questions upfront may prevent a callback and an unhappy customer. Suppose a technician is called out to service an ice machine that is not making any ice. Upon arriving at the job, the technician does not ask the customer any questions upfront and goes straight to the ice machine. The technician discovers the bin thermostat is defective, obtains an OK from the customer, replaces the part, collects the cost of the repair, and leaves. The next day the customer calls the shop complaining the ice machine is not making enough ice.
When the technician arrives back on the job, he discovers a low refrigerant charge is the cause of the low ice production. There is a slow leak at the suction Schrader valve. The technician informs the customer of the problem and quotes an additional fee for the repair. The customer becomes upset because he assumed the repair of the machine yesterday had solved the problem. Apparently the ice machine had been producing ice slowly for the last four to five weeks, but the customer decided to live with the problem. Now after spending the money for the repair yesterday, he assumed the machine would be back to its original operating capacity.
If only the technician had spent some time with the customer yesterday. He would have discovered the low-capacity problem and looked at the machine a little closer after discovering the bin thermostat was defective. The technician would have discovered the low refrigerant charge and presented both problems to the customer. This would have saved time and money for both the customer and the technician.
There are many other situations where just asking a few pertinent questions can lead to discovering a system problem in a more proficient manner as well as preventing a misunderstanding between a customer and a technician. Spending a little extra time with a customer is definitely a valuable service tool.
Correction:My July 6 column contained an incorrect sentence in one of the paragraphs and was caught by an alert reader. The paragraph, with the correct sentence, should have read:
“A clamp-on analog ammeter meter can also be used to check the operation of this relay. Set the ammeter to a high scale. Clamp the ammeter around the wire connected to the “1” terminal of the relay. Apply voltage to the motor’s circuit. The needle of the meter should swing high and then drop to zero. If the needle does not move or moves and does not return to zero, there may be a problem with the relay. Disconnect the voltage applied to the circuit, remove the relay from the circuit, and using an ohmmeter, check the relay’s coil and contacts.”
Also, while the picture with the article showed the ohmmeter correctly, the contact should have been drawn closed.
Publication date: 09/07/2009
Ice Breaker: First Steps of Service Calls
September 7, 2009